ALSA: xen-front: Read sound driver configuration from Xen store

Read configuration values from Xen store according
to xen/interface/io/sndif.h protocol:
- introduce configuration structures for different
components, e.g. sound card, device, stream
- read PCM HW parameters, e.g rate, format etc.
- detect stream type (capture/playback)
- read device and card parameters

Signed-off-by: Oleksandr Andrushchenko <[e-mail]>
Signed-off-by: Takashi Iwai <[e-mail]>

sound/xen/Makefile

···
 # SPDX-License-Identifier: GPL-2.0 OR MIT
 
-snd_xen_front-objs := xen_snd_front.o
+snd_xen_front-objs := xen_snd_front.o \
+		      xen_snd_front_cfg.o
 
 obj-$(CONFIG_SND_XEN_FRONTEND) += snd_xen_front.o

sound/xen/xen_snd_front.c

···
 
 static int sndback_initwait(struct xen_snd_front_info *front_info)
 {
+	int num_streams;
+	int ret;
+
+	ret = xen_snd_front_cfg_card(front_info, &num_streams);
+	if (ret < 0)
+		return ret;
+
 	return 0;
 }
 

sound/xen/xen_snd_front.h

···
 #ifndef __XEN_SND_FRONT_H
 #define __XEN_SND_FRONT_H
 
+#include "xen_snd_front_cfg.h"
+
 struct xen_snd_front_info {
 	struct xenbus_device *xb_dev;
+
+	struct xen_front_cfg_card cfg;
 };
 
 #endif /* __XEN_SND_FRONT_H */

sound/xen/xen_snd_front_cfg.c

···
+// SPDX-License-Identifier: GPL-2.0 OR MIT
+
+/*
+ * Xen para-virtual sound device
+ *
+ * Copyright (C) 2016-2018 EPAM Systems Inc.
+ *
+ * Author: Oleksandr Andrushchenko <[e-mail]>
+ */
+
+#include <xen/xenbus.h>
+
+#include <xen/interface/io/sndif.h>
+
+#include "xen_snd_front.h"
+#include "xen_snd_front_cfg.h"
+
+/* Maximum number of supported streams. */
+#define VSND_MAX_STREAM		8
+
+struct cfg_hw_sample_rate {
+	const char *name;
+	unsigned int mask;
+	unsigned int value;
+};
+
+static const struct cfg_hw_sample_rate CFG_HW_SUPPORTED_RATES[] = {
+	{ .name = "5512",   .mask = SNDRV_PCM_RATE_5512,   .value = 5512 },
+	{ .name = "8000",   .mask = SNDRV_PCM_RATE_8000,   .value = 8000 },
+	{ .name = "11025",  .mask = SNDRV_PCM_RATE_11025,  .value = 11025 },
+	{ .name = "16000",  .mask = SNDRV_PCM_RATE_16000,  .value = 16000 },
+	{ .name = "22050",  .mask = SNDRV_PCM_RATE_22050,  .value = 22050 },
+	{ .name = "32000",  .mask = SNDRV_PCM_RATE_32000,  .value = 32000 },
+	{ .name = "44100",  .mask = SNDRV_PCM_RATE_44100,  .value = 44100 },
+	{ .name = "48000",  .mask = SNDRV_PCM_RATE_48000,  .value = 48000 },
+	{ .name = "64000",  .mask = SNDRV_PCM_RATE_64000,  .value = 64000 },
+	{ .name = "96000",  .mask = SNDRV_PCM_RATE_96000,  .value = 96000 },
+	{ .name = "176400", .mask = SNDRV_PCM_RATE_176400, .value = 176400 },
+	{ .name = "192000", .mask = SNDRV_PCM_RATE_192000, .value = 192000 },
+};
+
+struct cfg_hw_sample_format {
+	const char *name;
+	u64 mask;
+};
+
+static const struct cfg_hw_sample_format CFG_HW_SUPPORTED_FORMATS[] = {
+	{
+		.name = XENSND_PCM_FORMAT_U8_STR,
+		.mask = SNDRV_PCM_FMTBIT_U8
+	},
+	{
+		.name = XENSND_PCM_FORMAT_S8_STR,
+		.mask = SNDRV_PCM_FMTBIT_S8
+	},
+	{
+		.name = XENSND_PCM_FORMAT_U16_LE_STR,
+		.mask = SNDRV_PCM_FMTBIT_U16_LE
+	},
+	{
+		.name = XENSND_PCM_FORMAT_U16_BE_STR,
+		.mask = SNDRV_PCM_FMTBIT_U16_BE
+	},
+	{
+		.name = XENSND_PCM_FORMAT_S16_LE_STR,
+		.mask = SNDRV_PCM_FMTBIT_S16_LE
+	},
+	{
+		.name = XENSND_PCM_FORMAT_S16_BE_STR,
+		.mask = SNDRV_PCM_FMTBIT_S16_BE
+	},
+	{
+		.name = XENSND_PCM_FORMAT_U24_LE_STR,
+		.mask = SNDRV_PCM_FMTBIT_U24_LE
+	},
+	{
+		.name = XENSND_PCM_FORMAT_U24_BE_STR,
+		.mask = SNDRV_PCM_FMTBIT_U24_BE
+	},
+	{
+		.name = XENSND_PCM_FORMAT_S24_LE_STR,
+		.mask = SNDRV_PCM_FMTBIT_S24_LE
+	},
+	{
+		.name = XENSND_PCM_FORMAT_S24_BE_STR,
+		.mask = SNDRV_PCM_FMTBIT_S24_BE
+	},
+	{
+		.name = XENSND_PCM_FORMAT_U32_LE_STR,
+		.mask = SNDRV_PCM_FMTBIT_U32_LE
+	},
+	{
+		.name = XENSND_PCM_FORMAT_U32_BE_STR,
+		.mask = SNDRV_PCM_FMTBIT_U32_BE
+	},
+	{
+		.name = XENSND_PCM_FORMAT_S32_LE_STR,
+		.mask = SNDRV_PCM_FMTBIT_S32_LE
+	},
+	{
+		.name = XENSND_PCM_FORMAT_S32_BE_STR,
+		.mask = SNDRV_PCM_FMTBIT_S32_BE
+	},
+	{
+		.name = XENSND_PCM_FORMAT_A_LAW_STR,
+		.mask = SNDRV_PCM_FMTBIT_A_LAW
+	},
+	{
+		.name = XENSND_PCM_FORMAT_MU_LAW_STR,
+		.mask = SNDRV_PCM_FMTBIT_MU_LAW
+	},
+	{
+		.name = XENSND_PCM_FORMAT_F32_LE_STR,
+		.mask = SNDRV_PCM_FMTBIT_FLOAT_LE
+	},
+	{
+		.name = XENSND_PCM_FORMAT_F32_BE_STR,
+		.mask = SNDRV_PCM_FMTBIT_FLOAT_BE
+	},
+	{
+		.name = XENSND_PCM_FORMAT_F64_LE_STR,
+		.mask = SNDRV_PCM_FMTBIT_FLOAT64_LE
+	},
+	{
+		.name = XENSND_PCM_FORMAT_F64_BE_STR,
+		.mask = SNDRV_PCM_FMTBIT_FLOAT64_BE
+	},
+	{
+		.name = XENSND_PCM_FORMAT_IEC958_SUBFRAME_LE_STR,
+		.mask = SNDRV_PCM_FMTBIT_IEC958_SUBFRAME_LE
+	},
+	{
+		.name = XENSND_PCM_FORMAT_IEC958_SUBFRAME_BE_STR,
+		.mask = SNDRV_PCM_FMTBIT_IEC958_SUBFRAME_BE
+	},
+	{
+		.name = XENSND_PCM_FORMAT_IMA_ADPCM_STR,
+		.mask = SNDRV_PCM_FMTBIT_IMA_ADPCM
+	},
+	{
+		.name = XENSND_PCM_FORMAT_MPEG_STR,
+		.mask = SNDRV_PCM_FMTBIT_MPEG
+	},
+	{
+		.name = XENSND_PCM_FORMAT_GSM_STR,
+		.mask = SNDRV_PCM_FMTBIT_GSM
+	},
+};
+
+static void cfg_hw_rates(char *list, unsigned int len,
+			 const char *path, struct snd_pcm_hardware *pcm_hw)
+{
+	char *cur_rate;
+	unsigned int cur_mask;
+	unsigned int cur_value;
+	unsigned int rates;
+	unsigned int rate_min;
+	unsigned int rate_max;
+	int i;
+
+	rates = 0;
+	rate_min = -1;
+	rate_max = 0;
+	while ((cur_rate = strsep(&list, XENSND_LIST_SEPARATOR))) {
+		for (i = 0; i < ARRAY_SIZE(CFG_HW_SUPPORTED_RATES); i++)
+			if (!strncasecmp(cur_rate,
+					 CFG_HW_SUPPORTED_RATES[i].name,
+					 XENSND_SAMPLE_RATE_MAX_LEN)) {
+				cur_mask = CFG_HW_SUPPORTED_RATES[i].mask;
+				cur_value = CFG_HW_SUPPORTED_RATES[i].value;
+				rates |= cur_mask;
+				if (rate_min > cur_value)
+					rate_min = cur_value;
+				if (rate_max < cur_value)
+					rate_max = cur_value;
+			}
+	}
+
+	if (rates) {
+		pcm_hw->rates = rates;
+		pcm_hw->rate_min = rate_min;
+		pcm_hw->rate_max = rate_max;
+	}
+}
+
+static void cfg_formats(char *list, unsigned int len,
+			const char *path, struct snd_pcm_hardware *pcm_hw)
+{
+	u64 formats;
+	char *cur_format;
+	int i;
+
+	formats = 0;
+	while ((cur_format = strsep(&list, XENSND_LIST_SEPARATOR))) {
+		for (i = 0; i < ARRAY_SIZE(CFG_HW_SUPPORTED_FORMATS); i++)
+			if (!strncasecmp(cur_format,
+					 CFG_HW_SUPPORTED_FORMATS[i].name,
+					 XENSND_SAMPLE_FORMAT_MAX_LEN))
+				formats |= CFG_HW_SUPPORTED_FORMATS[i].mask;
+	}
+
+	if (formats)
+		pcm_hw->formats = formats;
+}
+
+#define MAX_BUFFER_SIZE		(64 * 1024)
+#define MIN_PERIOD_SIZE		64
+#define MAX_PERIOD_SIZE		MAX_BUFFER_SIZE
+#define USE_FORMATS		(SNDRV_PCM_FMTBIT_U8 | \
+				 SNDRV_PCM_FMTBIT_S16_LE)
+#define USE_RATE		(SNDRV_PCM_RATE_CONTINUOUS | \
+				 SNDRV_PCM_RATE_8000_48000)
+#define USE_RATE_MIN		5512
+#define USE_RATE_MAX		48000
+#define USE_CHANNELS_MIN	1
+#define USE_CHANNELS_MAX	2
+#define USE_PERIODS_MIN		2
+#define USE_PERIODS_MAX		(MAX_BUFFER_SIZE / MIN_PERIOD_SIZE)
+
+static const struct snd_pcm_hardware SND_DRV_PCM_HW_DEFAULT = {
+	.info = (SNDRV_PCM_INFO_MMAP |
+		 SNDRV_PCM_INFO_INTERLEAVED |
+		 SNDRV_PCM_INFO_RESUME |
+		 SNDRV_PCM_INFO_MMAP_VALID),
+	.formats = USE_FORMATS,
+	.rates = USE_RATE,
+	.rate_min = USE_RATE_MIN,
+	.rate_max = USE_RATE_MAX,
+	.channels_min = USE_CHANNELS_MIN,
+	.channels_max = USE_CHANNELS_MAX,
+	.buffer_bytes_max = MAX_BUFFER_SIZE,
+	.period_bytes_min = MIN_PERIOD_SIZE,
+	.period_bytes_max = MAX_PERIOD_SIZE,
+	.periods_min = USE_PERIODS_MIN,
+	.periods_max = USE_PERIODS_MAX,
+	.fifo_size = 0,
+};
+
+static void cfg_read_pcm_hw(const char *path,
+			    struct snd_pcm_hardware *parent_pcm_hw,
+			    struct snd_pcm_hardware *pcm_hw)
+{
+	char *list;
+	int val;
+	size_t buf_sz;
+	unsigned int len;
+
+	/* Inherit parent's PCM HW and read overrides from XenStore. */
+	if (parent_pcm_hw)
+		*pcm_hw = *parent_pcm_hw;
+	else
+		*pcm_hw = SND_DRV_PCM_HW_DEFAULT;
+
+	val = xenbus_read_unsigned(path, XENSND_FIELD_CHANNELS_MIN, 0);
+	if (val)
+		pcm_hw->channels_min = val;
+
+	val = xenbus_read_unsigned(path, XENSND_FIELD_CHANNELS_MAX, 0);
+	if (val)
+		pcm_hw->channels_max = val;
+
+	list = xenbus_read(XBT_NIL, path, XENSND_FIELD_SAMPLE_RATES, &len);
+	if (!IS_ERR(list)) {
+		cfg_hw_rates(list, len, path, pcm_hw);
+		kfree(list);
+	}
+
+	list = xenbus_read(XBT_NIL, path, XENSND_FIELD_SAMPLE_FORMATS, &len);
+	if (!IS_ERR(list)) {
+		cfg_formats(list, len, path, pcm_hw);
+		kfree(list);
+	}
+
+	buf_sz = xenbus_read_unsigned(path, XENSND_FIELD_BUFFER_SIZE, 0);
+	if (buf_sz)
+		pcm_hw->buffer_bytes_max = buf_sz;
+
+	/* Update configuration to match new values. */
+	if (pcm_hw->channels_min > pcm_hw->channels_max)
+		pcm_hw->channels_min = pcm_hw->channels_max;
+
+	if (pcm_hw->rate_min > pcm_hw->rate_max)
+		pcm_hw->rate_min = pcm_hw->rate_max;
+
+	pcm_hw->period_bytes_max = pcm_hw->buffer_bytes_max;
+
+	pcm_hw->periods_max = pcm_hw->period_bytes_max /
+		pcm_hw->period_bytes_min;
+}
+
+static int cfg_get_stream_type(const char *path, int index,
+			       int *num_pb, int *num_cap)
+{
+	char *str = NULL;
+	char *stream_path;
+	int ret;
+
+	*num_pb = 0;
+	*num_cap = 0;
+	stream_path = kasprintf(GFP_KERNEL, "%s/%d", path, index);
+	if (!stream_path) {
+		ret = -ENOMEM;
+		goto fail;
+	}
+
+	str = xenbus_read(XBT_NIL, stream_path, XENSND_FIELD_TYPE, NULL);
+	if (IS_ERR(str)) {
+		ret = PTR_ERR(str);
+		goto fail;
+	}
+
+	if (!strncasecmp(str, XENSND_STREAM_TYPE_PLAYBACK,
+			 sizeof(XENSND_STREAM_TYPE_PLAYBACK))) {
+		(*num_pb)++;
+	} else if (!strncasecmp(str, XENSND_STREAM_TYPE_CAPTURE,
+			      sizeof(XENSND_STREAM_TYPE_CAPTURE))) {
+		(*num_cap)++;
+	} else {
+		ret = -EINVAL;
+		goto fail;
+	}
+	ret = 0;
+
+fail:
+	kfree(stream_path);
+	kfree(str);
+	return ret;
+}
+
+static int cfg_stream(struct xen_snd_front_info *front_info,
+		      struct xen_front_cfg_pcm_instance *pcm_instance,
+		      const char *path, int index, int *cur_pb, int *cur_cap,
+		      int *stream_cnt)
+{
+	char *str = NULL;
+	char *stream_path;
+	struct xen_front_cfg_stream *stream;
+	int ret;
+
+	stream_path = devm_kasprintf(&front_info->xb_dev->dev,
+				     GFP_KERNEL, "%s/%d", path, index);
+	if (!stream_path) {
+		ret = -ENOMEM;
+		goto fail;
+	}
+
+	str = xenbus_read(XBT_NIL, stream_path, XENSND_FIELD_TYPE, NULL);
+	if (IS_ERR(str)) {
+		ret = PTR_ERR(str);
+		goto fail;
+	}
+
+	if (!strncasecmp(str, XENSND_STREAM_TYPE_PLAYBACK,
+			 sizeof(XENSND_STREAM_TYPE_PLAYBACK))) {
+		stream = &pcm_instance->streams_pb[(*cur_pb)++];
+	} else if (!strncasecmp(str, XENSND_STREAM_TYPE_CAPTURE,
+			      sizeof(XENSND_STREAM_TYPE_CAPTURE))) {
+		stream = &pcm_instance->streams_cap[(*cur_cap)++];
+	} else {
+		ret = -EINVAL;
+		goto fail;
+	}
+
+	/* Get next stream index. */
+	stream->index = (*stream_cnt)++;
+	stream->xenstore_path = stream_path;
+	/*
+	 * Check XenStore if PCM HW configuration exists for this stream
+	 * and update if so, e.g. we inherit all values from device's PCM HW,
+	 * but can still override some of the values for the stream.
+	 */
+	cfg_read_pcm_hw(stream->xenstore_path,
+			&pcm_instance->pcm_hw, &stream->pcm_hw);
+	ret = 0;
+
+fail:
+	kfree(str);
+	return ret;
+}
+
+static int cfg_device(struct xen_snd_front_info *front_info,
+		      struct xen_front_cfg_pcm_instance *pcm_instance,
+		      struct snd_pcm_hardware *parent_pcm_hw,
+		      const char *path, int node_index, int *stream_cnt)
+{
+	char *str;
+	char *device_path;
+	int ret, i, num_streams;
+	int num_pb, num_cap;
+	int cur_pb, cur_cap;
+	char node[3];
+
+	device_path = kasprintf(GFP_KERNEL, "%s/%d", path, node_index);
+	if (!device_path)
+		return -ENOMEM;
+
+	str = xenbus_read(XBT_NIL, device_path, XENSND_FIELD_DEVICE_NAME, NULL);
+	if (!IS_ERR(str)) {
+		strncpy(pcm_instance->name, str, sizeof(pcm_instance->name));
+		kfree(str);
+	}
+
+	pcm_instance->device_id = node_index;
+
+	/*
+	 * Check XenStore if PCM HW configuration exists for this device
+	 * and update if so, e.g. we inherit all values from card's PCM HW,
+	 * but can still override some of the values for the device.
+	 */
+	cfg_read_pcm_hw(device_path, parent_pcm_hw, &pcm_instance->pcm_hw);
+
+	/* Find out how many streams were configured in Xen store. */
+	num_streams = 0;
+	do {
+		snprintf(node, sizeof(node), "%d", num_streams);
+		if (!xenbus_exists(XBT_NIL, device_path, node))
+			break;
+
+		num_streams++;
+	} while (num_streams < VSND_MAX_STREAM);
+
+	pcm_instance->num_streams_pb = 0;
+	pcm_instance->num_streams_cap = 0;
+	/* Get number of playback and capture streams. */
+	for (i = 0; i < num_streams; i++) {
+		ret = cfg_get_stream_type(device_path, i, &num_pb, &num_cap);
+		if (ret < 0)
+			goto fail;
+
+		pcm_instance->num_streams_pb += num_pb;
+		pcm_instance->num_streams_cap += num_cap;
+	}
+
+	if (pcm_instance->num_streams_pb) {
+		pcm_instance->streams_pb =
+				devm_kcalloc(&front_info->xb_dev->dev,
+					     pcm_instance->num_streams_pb,
+					     sizeof(struct xen_front_cfg_stream),
+					     GFP_KERNEL);
+		if (!pcm_instance->streams_pb) {
+			ret = -ENOMEM;
+			goto fail;
+		}
+	}
+
+	if (pcm_instance->num_streams_cap) {
+		pcm_instance->streams_cap =
+				devm_kcalloc(&front_info->xb_dev->dev,
+					     pcm_instance->num_streams_cap,
+					     sizeof(struct xen_front_cfg_stream),
+					     GFP_KERNEL);
+		if (!pcm_instance->streams_cap) {
+			ret = -ENOMEM;
+			goto fail;
+		}
+	}
+
+	cur_pb = 0;
+	cur_cap = 0;
+	for (i = 0; i < num_streams; i++) {
+		ret = cfg_stream(front_info, pcm_instance, device_path, i,
+				 &cur_pb, &cur_cap, stream_cnt);
+		if (ret < 0)
+			goto fail;
+	}
+	ret = 0;
+
+fail:
+	kfree(device_path);
+	return ret;
+}
+
+int xen_snd_front_cfg_card(struct xen_snd_front_info *front_info,
+			   int *stream_cnt)
+{
+	struct xenbus_device *xb_dev = front_info->xb_dev;
+	struct xen_front_cfg_card *cfg = &front_info->cfg;
+	int ret, num_devices, i;
+	char node[3];
+
+	*stream_cnt = 0;
+	num_devices = 0;
+	do {
+		snprintf(node, sizeof(node), "%d", num_devices);
+		if (!xenbus_exists(XBT_NIL, xb_dev->nodename, node))
+			break;
+
+		num_devices++;
+	} while (num_devices < SNDRV_PCM_DEVICES);
+
+	if (!num_devices) {
+		dev_warn(&xb_dev->dev,
+			 "No devices configured for sound card at %s\n",
+			 xb_dev->nodename);
+		return -ENODEV;
+	}
+
+	/* Start from default PCM HW configuration for the card. */
+	cfg_read_pcm_hw(xb_dev->nodename, NULL, &cfg->pcm_hw);
+
+	cfg->pcm_instances =
+			devm_kcalloc(&front_info->xb_dev->dev, num_devices,
+				     sizeof(struct xen_front_cfg_pcm_instance),
+				     GFP_KERNEL);
+	if (!cfg->pcm_instances)
+		return -ENOMEM;
+
+	for (i = 0; i < num_devices; i++) {
+		ret = cfg_device(front_info, &cfg->pcm_instances[i],
+				 &cfg->pcm_hw, xb_dev->nodename, i, stream_cnt);
+		if (ret < 0)
+			return ret;
+	}
+	cfg->num_pcm_instances = num_devices;
+	return 0;
+}
+

sound/xen/xen_snd_front_cfg.h

···
+/* SPDX-License-Identifier: GPL-2.0 OR MIT */
+
+/*
+ * Xen para-virtual sound device
+ *
+ * Copyright (C) 2016-2018 EPAM Systems Inc.
+ *
+ * Author: Oleksandr Andrushchenko <[e-mail]>
+ */
+
+#ifndef __XEN_SND_FRONT_CFG_H
+#define __XEN_SND_FRONT_CFG_H
+
+#include <sound/core.h>
+#include <sound/pcm.h>
+
+struct xen_snd_front_info;
+
+struct xen_front_cfg_stream {
+	int index;
+	char *xenstore_path;
+	struct snd_pcm_hardware pcm_hw;
+};
+
+struct xen_front_cfg_pcm_instance {
+	char name[80];
+	int device_id;
+	struct snd_pcm_hardware pcm_hw;
+	int  num_streams_pb;
+	struct xen_front_cfg_stream *streams_pb;
+	int  num_streams_cap;
+	struct xen_front_cfg_stream *streams_cap;
+};
+
+struct xen_front_cfg_card {
+	char name_short[32];
+	char name_long[80];
+	struct snd_pcm_hardware pcm_hw;
+	int num_pcm_instances;
+	struct xen_front_cfg_pcm_instance *pcm_instances;
+};
+
+int xen_snd_front_cfg_card(struct xen_snd_front_info *front_info,
+			   int *stream_cnt);
+
+#endif /* __XEN_SND_FRONT_CFG_H */